C++ Special Member Function Guidelines

The C++ special member functions are:

• default constructor
• copy constructor
• move constructor
• destructor
• copy assignment
• move assignment

They can be either = defaulted, = deleted, not manually written at all, or have a custom implementation.

The majority of classes you write will match one of the four options listed below. When in doubt, do what normal does (rule of zero).

class normal
{
public:
    normal(); // if it makes sense
    ~normal() = default;

    normal(const normal&) = default;
    normal(normal&&)      = default;

    normal& operator=(const normal&) = default;
    normal& operator=(normal&&)      = default;
};

class immoveable
{
public:
    immoveable(); // if it makes sense
    ~immoveable() = default;

    immoveable(const immoveable&)            = delete; 
    immoveable& operator=(const immoveable&) = delete;

    immoveable(immoveable&&)            = delete;
    immoveable& operator=(immoveable&&) = delete;
};

class container
{
public:
    container() noexcept;
    ~container() noexcept;

    container(const container& other);
    container(container&& other) noexcept;

    container& operator=(const container& other);
    container& operator=(container&& other) noexcept;
};

class resource_handle
{
public:
    resource_handle() noexcept;
    ~resource_handle() noexcept;

    resource_handle(const resource_handle&)            = delete;
    resource_handle& operator=(const resource_handle&) = delete;

    resource_handle(resource_handle&& other) noexcept;
    resource_handle& operator=(resource_handle&& other) noexcept;
};

Shown in italics are the effective compiler-generated implementations of the special members; you can write them yourself to be explicit.

Full rationale and further explanations: Tutorial: When to Write Which Special Member